Parent-IFrame Communication

I created a HTML web resource on a form. This HTML generates an iFrame dynamically. It also needs to listen to requests coming from the child iFrame and blink/stop blinking the browser's tab.

Our dynamics CRM is over HTTP and the iFrame is over HTTPS.

This is the HTML:

community.dynamics.com/.../demo.txt

Inside the iFrame, which we do not have access to as it is in another domain, the postMessage API is used to send data to the parent HTML like so: 

window.parent.postMessage(JSON.stringify({active: 1}), "http://path/to/our/org"); // our CRM is over HTTP

but the debugger inside messageHandler will not be hit.

The checkbox restrict cross-frame scripting is unmarked.

We are using Dynamics CRM v8.1 on-premise if that matters.